From: Cong Wang <cwang@twopensource.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Dominick Grift <dac.override@gmail.com>, netdev <netdev@vger.kernel.org>
Subject: Re: Suspicious RCU usage in bridge with Linux v4.0-9362-g1fc149933fd4
Date: Mon, 4 May 2015 14:38:23 -0700 [thread overview]
Message-ID: <CAHA+R7OD7Bh52MkB1hKs8DdncrgBN2_1VYQwrFGetJFJ7chgyg@mail.gmail.com> (raw)
In-Reply-To: <1430772572.27254.3.camel@edumazet-glaptop2.roam.corp.google.com>
On Mon, May 4, 2015 at 1:49 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Mon, 2015-05-04 at 11:45 -0700, Cong Wang wrote:
>> On Mon, May 4, 2015 at 6:39 AM, Dominick Grift <dac.override@gmail.com> wrote:
>> > On Thu, Apr 23, 2015 at 01:07:45PM -0400, Josh Boyer wrote:
>> >> Hi All,
>> >>
>> >> We've had a user report the following backtrace from the bridge module
>> >> with a recent Linus' tree. Has anything like this been reported yet?
>> >> If you have any questions on setup, the user is CC'd.
>> >>
>> >> josh
>> >>
>> >> [ 29.382235] br0: port 1(tap0) entered forwarding state
>> >>
>> >> [ 29.382286] ===============================
>> >> [ 29.382315] [ INFO: suspicious RCU usage. ]
>> >> [ 29.382344] 4.1.0-0.rc0.git11.1.fc23.x86_64 #1 Not tainted
>> >> [ 29.382380] -------------------------------
>> >> [ 29.382409] net/bridge/br_private.h:626 suspicious
>> >> rcu_dereference_check() usage!
>> >
>> > <snip>
>> >
>> > With 4.1.0-0.rc1.git1.1.fc23.x86_64 the situation seems to have slightly changed:
>> >
>>
>> Should be the same issue. Please give the attached patch a try,
>> it is compile-tested only.
>>
>> Thanks!
>
> Please send inline patches, otherwise its hard for us to review them and
> give feedback.
Compile-test only patch is never ready for review, I thought it is too obvious
to mention.
>
> At first glance, it is way too complicated.
>
> br_get_vlan_info() change is not needed :
>
> rcu_dereference_rtnl() can already be used from RCU or RTNL protected
> code.
>
> (Quite different from rtnl_dereference())
>
> What about :
Feel free to submit a formal patch, I apparently don't have time to read more
into this, nor have time to argument on details.
Thanks.
next prev parent reply other threads:[~2015-05-04 21:38 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-23 17:07 Suspicious RCU usage in bridge with Linux v4.0-9362-g1fc149933fd4 Josh Boyer
2015-04-23 17:35 ` Sudeep Holla
2015-04-23 22:53 ` Cong Wang
2015-05-04 13:39 ` Dominick Grift
2015-05-04 18:45 ` Cong Wang
2015-05-04 20:27 ` Stephen Hemminger
2015-05-04 21:35 ` Cong Wang
2015-05-11 13:15 ` Dominick Grift
2015-05-11 14:53 ` Eric Dumazet
2015-05-11 17:42 ` Dominick Grift
2015-05-12 0:13 ` poma
2015-05-12 0:37 ` Eric Dumazet
2015-05-12 1:33 ` poma
2015-05-12 18:27 ` Dominick Grift
2015-05-21 19:22 ` Josh Boyer
2015-05-21 20:06 ` Eric Dumazet
2015-05-05 2:32 ` Vlad Yasevich
2015-05-04 20:49 ` Eric Dumazet
2015-05-04 21:38 ` Cong Wang [this message]
2015-05-04 22:06 ` Eric Dumazet
2015-05-04 22:17 ` Cong Wang
2015-05-04 22:29 ` Eric Dumazet
2015-05-04 22:44 ` Cong Wang
2015-05-04 23:00 ` Eric Dumazet
2015-05-04 23:22 ` David Miller
2015-05-05 8:33 ` Dominick Grift
2015-05-21 20:28 ` [PATCH net] bridge: fix lockdep splat Eric Dumazet
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